Article ; Online: Covalent Si–H Bonds in the Zintl Phase Hydride CaSiH 1+ x ( x ≤ 1/3)
Inorganics, Vol 7, Iss 9, p
2019 Volume 106
Abstract: The crystal structure of the Zintl phase hydride CaSiH ≈4/3 was discussed controversially, especially with respect to the nature of the silicon-hydrogen interaction. We have applied X-ray and neutron powder diffraction as well as total neutron scattering ...
Abstract | The crystal structure of the Zintl phase hydride CaSiH ≈4/3 was discussed controversially, especially with respect to the nature of the silicon-hydrogen interaction. We have applied X-ray and neutron powder diffraction as well as total neutron scattering on a deuterated sample, CaSiD 1.1 . Rietveld refinement (CaSiD 1.1 , Pnma , a = 14.579(4) Å, b = 3.8119(4) Å, c = 11.209(2) Å) and an analysis of the neutron pair distribution function show a silicon-deuterium bond length of 1.53 Å. The Si−H bond may thus be categorized as covalent and the main structural features described by a limiting ionic formula Ca 2+ H − (Si − ) 2/3 (SiH − ) 1/3 . Hydrogen atoms decorating the ribbon-like silicon polyanion made of three connected zigzag chains are under-occupied, resulting in a composition CaSiH 1.1 . Hydrogen-poor Zintl phase hydrides CaSiH <1 with hydride ions in Ca 4 tetrahedra only were found in an in situ neutron diffraction experiment at elevated temperature. Hydrogen (deuterium) uptake and release in CaSiD x (0.05 ≤ x ≤ 0.17) is a very fast process and takes less than 1 min to complete, which is of importance for possible hydrogen storage applications. |
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Keywords | Zintl phase ; Zintl phase hydride ; metal hydride ; neutron diffraction ; Rietveld refinement ; pair distribution function ; polyanions ; hydrogen storage ; silicon ; in situ ; Inorganic chemistry ; QD146-197 |
Subject code | 290 |
Language | English |
Publishing date | 2019-08-01T00:00:00Z |
Publisher | MDPI AG |
Document type | Article ; Online |
Database | BASE - Bielefeld Academic Search Engine (life sciences selection) |
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